On-Line Process Monitoring and Electric Submetering at Six

Municipal Wastewater Treatment Plants

Final Report 98-12 July 1998

New York State Energy Research and Development Authority

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State of New York Energy Research and Development Authority George E. Pataki William R. Howell, Chairman Governor F. William Valentino, President

http:http://www.nyserda.org

ON-LINE PROCESS MONITORING AND

ELECTRIC SUBMETERING AT SIX MUNICIPAL

WASTEWATER TREATMENT PLANTS

Final Report

Prepared for

THE NEW YORK STATE

ENERGY RESEARCH AND DEVELOPMENT AUTHORITY

Albany,NY

LaWTence J.Pakenas,P.E.

Senior Project Manager

and

EMPIRE STATE ELECTRIC ENERGY RESEARCH CORPORATION

and

ELECTRIC POWER RESEARCH INSTITUTE

Prepared by

CH2M HILL INC. Parsippany, NJ

Linda Ferguson

Technical Project Leader

Peter Keenan

Project Manager

and

SAIC-ENERGY SOLUTIONS DIVISION Albany, NY

Ron Slosberg Technical Project Leader

3172-ERTER-MW-94 NYSERDA Report 98-12 July 1998

NOTICE

This report was prepared by CH2M HILL Inc. and SAIC - Energy Solutions Division in the course

of performing work contracted for and sponsored by the New York State Energy Research and

Development Authority, the Empire State Electric Energy Research Corporation, and the Electric

Power Research Institute (hereafter the "Sponsors"). The opinions expressed in this report do not

necessarily reflect those of the Sponsors or the State of New York, and reference to any specific

product, service, process, or method does not constitute an implied or expressed recommendation

or endorsement of it. Further, the Sponsors and the State of New York make no warranties or

representations, expressed or implied, as to the fitness for particular purpose or merchantability

of any product, apparatus, or service, or the usefulness, completeness, or accuracy of any

processes, methods, or other information contained, described, disclosed, or referred to in this

report. The Sponsors, the State of New York, and the contractor make no repre~entation that the

use of any product, apparatus, process, method, or other information will not infringe privately

owned rights and will assume no liability for any loss, injury, or damage resulting from, or

occurring in connection with, the use of information contained, described, disclosed, or referred

to in this report.

ABSTRACT

An investigation was made of New York State wastewater treatment plants (WWTPs) to

determine if process audit and electrical submetering techniques are an effective method of

identifying energy conservation opportunities (ECOs) at municipal wastewater treatment plants.

The study at six municipal WWTPs included a range of facility sizes, locations, and treatment

technologies. A combination of online process monitoring, offline sampling, electrical

submetering, and specific performance efficiency testing techniques was used to obtain real-time

process and electrical consumption data.

Recommendations varied for each site. They included piping modifications, pump and/or motor

replacement, operational procedures changes, modification of online instrumentation and control

systems, aeration system upgrades, and additional energy reuse options. The energy implications

(savings or additional costs) were quantified for each item. The simple payback period for

operational changes and minor capital items ranged from 0 to 15 years. Major capital items were

recommended for reasons other than energy conservation, including worker health and safety,

effluent quality, and/or capacity limitations.

The results of the study indicated that the audit approach, which consists of a systematic and

rigorous methodology for obtaining accurate performance information, is an appropriate tool for

identifying ECOs at existing wastewater treatment facilities. Online process data, equipment

performance characteristics, and electrical submetering information provide a good basis for

identifying ECOs, quantifying the achievable savings, and predicting the impact of implemen

tation on facility performance.

iii

TABLE OF CONTENTS

Section Page

1. Introduction....................................................................................................................................... 1-1

Project Objectives ............................................................................................................................... 1-1

Test Methodology .............................................................................................................................. 1-2

Test Sites ............................................................................................................................................. 1-3

2. Wastewater Treatment Plant Configurations and Performance .............................................. 2-1

Sodus Village WWTP ........................................................................................................................ 2-1

Performance History .................................................................................................................. 2-4

Field Test. ..................................................................................................................................... 2-5

Village of Goshen WWTP ................................................................................................................. 2-9

Performance History ................................................................................................................ 2-11

Field Test. ................................................................................................................................... 2-13

Marsh Creek WWTP ....................................................................................................................... 2-15

Performance History ................................................................................................................ 2-18

Field Test. ................................................................................................................................... 2-19

Arlington Sewage Treatment Plant ............................................................................................... 2-22

Performance History ................................................................................................................ 2-26

Field Test. ................................................................................................................................... 2-27

Bergen Point WWTP ........................................................................................................................ 2-30

Performance History ................................................................................................................ 2-33

Field Test .................................................................................................................................... 2-34

Yonkers Joint WWTP ....................................................................................................................... 2-38

Performance History ................................................................................................................ 2-41

Field Test. ................................................................................................................................... 2-43

3. Wastewater Treatment Plant Energy Usage ................................................................................. 3-1

Electrical Usage Profile ..................................................................................................................... 3-1

Sodus WWTP .............................................................................................................................. 3-1

Goshen WWTP ............................................................................................................................ 3-3

Marsh Creek WWTP .................................................................................................................. 3-3

Arlington STP .............................................................................................................................. 3-6

Bergen Point WWTP .................................................................................................................. 3-6

Yonkers Joint WWTP ................................................................................................................. 3-9

Standardized Electrical Usage ......................................................................................................... 3-9

4. Energy Conservation Opportunities ............................................................................................. 4-1

Sodus Village WWTP ........................................................................................................................ 4-1

Village of Goshen WWTP ................................................................................................................. 4-4

Marsh Creek WWTP ......................................................................................................................... 4-5

Arlington STP ..................................................................................................................................... 4-8

Bergen Point WWTP ........................................................................................................................ 4-11

Yonkers Joint WWTP ....................................................................................................................... 4-14

5. Conclusions ....................................................................................................................................... 5-1

Appendix A Equipment Used in the Submetering Program

v

TABLES

Number Page

1-1 Six Municipal Wastewater Treatment Plants Included in the Test Program ........................... 1-3

2-5 Village of Goshen WWTP - Summary of Unit Process Loading During Field Test

3-1 Standardized Electrical Consumption of the Major Unit Processes at the Six Wastewater

3-2 Electrical Consumption of Secondary Treatment at the Six Wastewater Treatment

4-2 Sodus Village WWTP - Costs of Small Capital and Operational Changes

4-3 Sodus Village WWTP - Life Cycle Cost Analysis of Major Recommended Capital

4-5 Village of Goshen WWTP - Costs of Small Capital and Operational Changes (in priority

4-12 Bergen Point WWTP - Costs of Recommended Small Capital and Operational Changes

2-1 Sodus Village WWTP - Summary of Unit Processes ................................................................... 2-3

2-2 Sodus Village WWTP - Summary of Unit Process Loading During Field Test Program....... 2-6

2-3 Sodus Village WWTP - Field Test Program .................................................................................. 2-7

2-4 Village of Goshen WWTP - Summary of Unit Processes .......................................................... 2-11

Program........................................................................................................................................... 2-13

2-6 Village of Goshen WWTP - Field Test Program ......................................................................... 2-14

2-7 Marsh Creek WWTP - Summary of Unit Processes .................................................................. 2-17

2-8 Marsh Creek WWTP - Summary of Unit Process Loading During Field Test Program ...... 2-20

2-9 Marsh Creek WWTP - Field Test Program ................................................................................ 2-21

2-10 Arlington STP - Summary of Unit Processes ............................................................................. 2-24

2-11 Arlington STP - Summary of Unit Process Loading During Field Test Program.................. 2-28

2-12 Arlington STP - Field Test Program ............................................................................................ 2-29

2-13 Bergen Point WWTP - Summary of Unit Processes ................................................................... 2-32

2-14 Bergen Point WWTP - Summary of Unit Process Loading During Field Test Program ...... 2-35

2-15 Bergen Point WWTP - Field Test Program ................................................................................. 2-36

2-16 Yonkers Joint WWTP - Summary of Unit Processes ................................................................. 2-40

2-17 Yonkers Joint WWTP - Summary of Unit Process Loading During Field Test Program ..... 2-44

2-18 Yonkers Joint WWTP - Field Test Program ................................................................................ 2-46

Treatment Plants ............................................................................................................................ 3-11

Plants ............................................................................................................................................... 3-13

4-1 Sodus Village WWTP - Identified Energy Conservation Opportunities .................................. 4-2

(in priority order) ............................................................................................................................. 4-3

Improvement .................................................................................................................................... 4-5

4-4 Village of Goshen WWTP - Identified Energy Conservation Opportunities ........................... 4-6

order) ................................................................................................................................................. 4-6

4-6 Village of Goshen WWTP - Life Cycle Cost Analysis of Major Capital Improvements ......... 4-8

4-7 Marsh Creek WWTP - Identified Energy Conservation Opportunities .................................... 4-8

4-8 Arlington STP - Identified Energy Conservation Opportunities ............................................. 4-11

4-9 Arlington STP - Costs of Small Capital and Operational Changes (in priority order) ......... 4-12

4-10 Arlington STP - Life Cycle Cost Analysis of Major Capital Improvements ........................... 4-15

4-11 Bergen Point WWTP - Identified Energy Conservation Opportunities ................................. 4-16

(in priority order) ........................................................................................................................... 4-17

4-13 Bergen Point WWTP - Life Cycle Cost Analysis of Major Capital Improvement ................. 4-19

4-14 Yonkers Joint WWTP - Identified Energy Conservation Opportunities ................................ 4-20

4-15 Yonkers Joint WWTP - Costs of ECO (in Priority Order) ......................................................... 4-22

vi

FIGURES

Number Page

2-1 Sodus WWTP - Process Flow Schematic ....................................................................................... 2-2

2-2 Goshen WWTP - Process Flow Schematic .................................................................................. 2-10

2-3 Marsh Creek WWTP - Process Flow Schematic ......................................................................... 2-16

2-4 Arlington STP - Process Flow Schematic .................................................................................... 2-23

2-5 Bergen Point WWTP - Process Flow Schematic ......................................................................... 2-31

2-6 Yonkers Joint WWTP - Process Flow Schematic ........................................................................ 2-39

3-1 Sodus WWTP - Energy Use of the Major Unit Processes ........................................................... 3-2

3-2 Goshen WWTP - Energy Use of the Major Unit Process ............................................................ 3-4

3-3 Marsh Creek WWTP - Energy Use of the Major Unit Processes ............................................... 3-5

3-4 Arlington STP - Energy Use of the Major Unit Processes ........................................................... 3-7

3-5 Bergen Point WWTP - Energy Use of the Major Unit Processes ................................................ 3-8

3-6 Yonkers Joint WWTP - Energy Use of the Major Unit Processes ............................................. 3-10

vii

ABBREVIATIONS

BODs 5-day biochemical oxygen demand

BFP belt filter press

Btu British thermal units

cBODs carbonaceous biochemical oxygen demand

COD chemical oxygen demand

OAF dissolved air flotation

DO dissolved oxygen

ECO energy conservation opportunities

F/Mv food to microorganism ratio

gpd gallons per day

gpm gallons per minute

hp horsepower

HRT hydraulic residence time

kW kilowatts

kWh kilowatt hours

Ibid pounds per day

mgd million gallons per day

mg/L milligram per liter

mL/g milliliter per gram

MLSS mixed liquor suspended solids

MLVSS mixed liquor volatile suspended solids

~-N ammonia as nitrogen

N02-N nitrite as nitrogen

N03-N nitrate as nitrogen

P04 orthophosphate

sBODs soluble biochemical oxygen demand

RAS return activated sludge

SOR surface overflow rate

SOTE standard oxygen transfer efficiency

SRT solids residence time

SVI sludge volume index

TKN total Kjeldahl nitrogen

TP total phosphorus

TS total solids

TSS total suspended solids

VS volatile solids

VSD variable speed drive

VSS volatile suspended solids

WAS waste activated sludge

viii

SUMMARY

The New York State Energy Research and Development Authority (NYSERDA), the Empire State

Electric Energy Research Corporation (ESEERCO), and the Electrical Power Research Institute

(EPRI) funded an investigation of New York State wastewater treatment plants (WWTPs). The

purpose of the investigation was to determine if process audit and electrical submetering tech

niques are an effective method of identifying energy conservation opportunities (ECOs) at

municipal wastewater treatment plants. Phase 1 consisted of screening 80 potential WWTPs to

identify six test sites to include in the study program. The sites were selected to provide a

representative sample of the existing wastewater treatment facilities in New York State in terms

of size (flow rate), location, treatment technologies, and sludge management practices. Table 1

lists the sites and their rated capacities. Table 2 lists the various treatment technologies included

in the test program. Phase 2 consisted of an intensive four- to six-week field study at each site

including operating data reviews, online process monitoring, offline sampling, performance

efficiency testing, and electrical submetering. The objectives of the field testing were to quantify

the energy consumption and process performance on a process-by-process and whole plant basis,

to examine the dynamic interrelationships among the unit processes to determine load/response

and effect on performance, and to identify areas for process improvements.

The ECOs identified during the study can be divided into four categories:

• maintenance and housekeeping items,

• operating and control procedures,

• electrical equipment replacement, and

• capacity-related issues.

TABLEt

SIX MUNICIPAL WASTEWATER TREATMENT FACILITIES INCLUDED IN THE TEST PROGRAM

Name of Facility Utility Rated Capacity

SodusWVVTP, Sodus, NY Rochester Gas and Electric 0.5 mgd

Goshen WWTP, Goshen, NY Orange and Rockland 1.5mgd

Marsh Creek WWTP, Geneva, NY New York State Electric and Gas Corp. 4.0mgd

Arlington STP, Poughkeepsie, NY Central Hudson Gas and Electric 4.0mgd

Bergen Point WWTP, Babylon, NY Long Island Lighting Company 30.0mgd

Yonkers Joint WWTP, Yonkers, NY New York Power Authority 90.0mgd

S-l

TABLE 2

LIQUID AND SOLIDS TREATMENT TECHNOLOGIES INCLUDED IN THE TEST PROGRAM

Liquid Treatment Technology Solids Treatment Technology

Pump stations Thickeners

Gravity belt Aerated grit chambers Gravity

Primary clarifiers Dissolved air flotation

Activated sludge Dewatering

Extended aeration Belt filter press Contact stabilization CentrifugeConventional activated sludge

Anaerobic digestion Aeration systems

Sludge composting Coarse bubble Fine bubble Incineration Membrane panels Fluidized bed

Multiple hearthTrickling filters

Tertiary filtration

Effluent polishing lagoons/wetlands

Chlorination

Several maintenance and housekeeping items were identified during the study. Common items

included inoperable or worn backflow prevention valves on pumps, inappropriate or worn

pressure relief valves on aeration blowers, inappropriate valve or gate settings, and worn pumps.

The capital costs of replacing these items were usually very small and the payback period was

usually less than two years.

The study recommended changes to operating procedures at several of the plants. These included

changes to pump control strategies, provision of measurement and control of miscellaneous air

use for common air supply systems, and changes to solids handling procedures. The capital costs

for these changes were usually small to moderate and the payback period was usually less than

five years.

All of the wastewater treatment plants included in the study were more thart 20 years old, and

there have been technological advances since the original electrical equipment was installed. At

several sites the study recommended replacing older electrical motor and drive systems with

more efficient units. The capital costs of these recommendations were moderate and the payback

period was usually less than five years.

S-2

Excess capacity in one or more unit process was identified as contributing to increased energy

consumption at many of the sites. Excess blower capacity as a result of upgrading from coarse- to

fine-bubble aeration, excess aeration basin volume, and excess solids stabilization capacity were

identified. Recommendations included taking basins out of service, downsizing equipment, and

providing intermediate storage between processes to allow for different loading rates. At two of

the sites the study recommended that the facility use the excess capacity in the solids handling

and treatment systems to treat hauled sludge from neighbouring facilities as an income

generating opportunity. The capital costs of these recommendations varied from very low (taking

units out of service) to high (constructing hauled sludge receiving facilities). The payback period

varied from less than one year to more than 10 years.

This project used a combination of process audit, energy audit, and electrical submetering

techniques to identify low-capital-cost methods of improving the performance and energy

efficiency of six WWTPs in New York State. The plants were selected to provide a representative

sample in terms of size, location, and treatment technologies. The plants were operating well

within their effluent discharge requirements and provided good to excellent levels of treatment.

One of the primary objectives of the study was to determine if this approach is an effective

method of reducing WWTP operating costs and improving WWTP performance. There were

several advantages to this approach:

• Real-time data provides a greater understanding of the dynamic response characteristics

of the treatment processes. The impact of energy conservation recommendations on

treatment performance is easier to foresee if the real-time process performance data is

available.

• Measured electrical consumption data is required to determine the potential energy

savings associated with implementing ECOs. Using a single power draw measurement

may over- or underestimate the potential savings.

• Real-time process and performance data is required to evaluate theoretical versus

achievable energy savings associated with implementing ECOs. The data can also

indicate methods of increasing the achievable savings.

8-3

• Discrepancies or unexpected results in the data generated are good indicators of potential

areas of improved performance that may be overlooked using more traditional

approaches.

The audit approach, which consists of a systematic and rigorous methodology for oqtaining

accurate performance information, is an appropriate tool for identifying ECOs at existing

wastewater treatment facilities. Online process data, equipment performance characteristics, and

electrical submetering information are required to predict the effects of implementing ECOs. The

conceptual approach used for this project was quite simple. Measure what you have, what you

are using, and the performance achieved, and base decisions for improving performance

efficiency on the measured data.

5-4

Section 1

INTRODUCTION

PROJECT OBJECTIVES

The New York State Energy Research and Development Authority (NYSERDA), the Empire State

Electric Energy Research Corporation (ESEERCO), and the Electric Power Research Institute

(EPRI) jointly funded an investigation of New York State wastewater treatment plants (WWTPs).

The purpose of the investigation was to determine if process optimization of the WWTPs without

major capital expenditure and the identification of potential energy-saving measures within

existing facilities were effective methods of reducing plant operating costs and improving plant

performance.

The project was conducted in two phases. Phase I, which was completed in 1995, consisted of

screening 80 potential WWTPs to identify six test sites for the field monitoring portion of the

project. The intent was to provide a representative sample of the WWTPs in New York State in

terms of size (flow rate), treatment technologies, and sludge management practices.

Phase 2 used a combination of operating data review, online process monitoring, offline

sampling, electrical submetering, and specific performance efficiency testing techniques to

quantify the treatment provided and energy consumed on a unit process and whole plant basis.

The overall objectives of the field testing were to:

• quantify the energy consumption and process performance on a process

by-process and whole plant basis at each WWTP;

• examine the dynamic interrelationships among the various unit

processes at each site, including loading response and its effect, on unit

process and whole plant energy use, performance, and treatment

efficiency;

• identify areas for process improvements including making changes to

treatment process control and operating procedures or installing electro

technologies, and low-capital-cost equipment changes, to improve

energy efficiency, treatment performance, and capacity at each WWTP.

1·1

TEST METHODOLOGY

The facility performance was evaluated in detail over a four- to six-week period. A minimum of

12 months of operating data was reviewed to determine the current baseline unit process loading

and performance and energy consumption pattern, and to identify factors that may be limiting

the facility performance.

The offline sampling consisted of collection and analysis of 24-hour composite samples from

upstream and downstream of each unit process supplemented with grab samples from various

locations. The analytical results were used to determine unit process loading and performance on

a daily basis and to characterize recycle streams through the plant. The offline sampling also

provided a quality control check for the online process data collected.

Real-time data was collected from the existing and temporary online process monitoring

equipment. The types of online process data collected varied between sites. In general, the data

included wastewater flow, air flow, aeration basin dissolved oxygen concentration, mixed liquor

concentration, return activated sludge flow, and effluent suspended solids concentration. The

online process data was used to quantify the dynamic load/response characteristics of the unit

processes.

The whole-facility energy use was recorded on a IS-minute basis by the local utility. The energy

use of the process-related equipment was monitored with temporary submetering equipment

installed during the field test period. For motors where the load was not expected to vary

significantly during use, time-in-use loggers were installed to record off!on events. Current

transducers and voltage-potential wires were installed at the breaker panel for motors that

experience significant variations in loading during normal operation.

Specific performance tests were conducted on the major energy end users to obtain in situ

performance data. Performance testing consisted of oxygen transfer efficiency testing, digester

tracer testing, and IIwire to waterll efficiency testing of the major process equipment.

The detailed results of the field work are presented in a separate site report for each facility.

Copies of the individual site reports are available through NYSERDA. This report presents a

summary of results from the six wastewater treatment plants included in the study.

1·2

TEST SITES

Table 1-1 lists the six municipal wastewater treatment plants and the corresponding treatment

technologies included in the study. The facilities ranged in size from 0.5 mgd to 90 mgd capacity

and included two small « 2 mgd), two medium (2 to 10 mgd), and two large (> 10 mgd) plants.

All of the sites provided a minimum of secondary level treatment. The two smaller sites also

provided tertiary treatment.

TABLE 1-1

SIX MUNICIPAL WASTEWATER TREATMENT PLANTS

INCLUDED IN THE TEST PROGRAM

Name Capacity Liquid Treatment (mgd) Processes

Sodus Village 0.5 Grit channel WWTP Primary clarification

Trickling filter Extended aeration Fine bubble aeration Tertiary sand filter

Village of Goshen 1.5 Grit channel WWTP Primary clarification

Trickling filter Treatment wetlands Chlorination

Marsh Creek 4.0 Aerated grit removal WWTP Primary clarification

Complete mix AS Panel membrane aeration Chlorination

Arlington STP 4.0 Aerated grit removal Primary clarification Plug flow AS Coarse bubble aeration Chlorination

Bergen Point 30 Scavenger waste facility WWTP Raw sewage pumping

Aerated grit removal Primary clarification Step feed AS Panel membrane aeration Chlorination

Yonkers Joint 90 Aerated grit removal WWTP Primary clarification

Plug flow AS Coarse bubble cross roll

aeration Chlorination

Solids Treatment Processes

Anaerobic digestion Sludge drying

Anaerobic digestion Sludge drying

Gravity thickening Anaerobic digestion Beltpress dewatering Composting

Gravity thickening Beltpress dewatering Fluidized bed incineration

Gravity thickening Gravity belt thickening Belt press dewatering Multiple hearth incineration

Gravity thickening Dissolved air flotation Anaerobic digestion Centrifuge dewatering

1-3

Section 2

WASTEWATER TREATMENT PLANT CONFIGURATIONS AND PERFORMANCE

The six wastewater treatment plants included in the study were chosen to provide a representative

sample of the range of facility sizes, locations, and treatment technologies currently operating in

New York State. The following sections provide a brief description of each facility, its recent

perfonnance history, and the field test procedures and results.

Field testing consisted of offline sampling, online monitoring, and perfonnance testing of specific

equipment and processes. The offline sample results are based on 24-hour composite samples and

grab samples taken at various points in the process. The online data consists of data measured from

temporary instruments installed for the test period, supplementing the data collected by the existing

pennanent online metering equipment at each site.

SODUS VILLAGE WWTP

Figure 2-1 presents a flow schematic and Table 2-1 summarizes the unit processes of the Sodus

Village WWTP. The rated capacity of the WWTP is 0.5 mgd and the current measured average-day

flow is 0.38 mgd. The WWTP discharge permit has seasonal limits for 5-day biochemical oxygen

demand (BODs), total suspended solids (TSS), and ammonia-nitrogen (NH,-N). During the summer

months the criteria are 5 mg/L, 10 mg/L, and 2.0 mg/L, for BODS' TSS, and NH,-N, respectively.

The dissolved oxygen (DO) concentration of the final effluent must be greater than 7 mg/L. During

the winter months the criteria are 25 mg/L and 30 mg/L for BODs and TSS, respectively. There is no

NH,-N discharge criterion for the winter months.

Raw wastewater flows by gravity through a grit channel prior to entering the primary clarifier. Grit

removed from the wastewater in this channel is disposed of offsite. The degritted wastewater flows

by gravity to a single primary clarifier. Filter backwash from the tertiary sand filter, digester

supernatant, and sludge concentrator supernatant is mixed with degritted wastewater upstream of

the primary clarifier. Sludge from the primary clarifier is pumped to the sludge well.

Following primary clarification, the wastewater flows by gravity to the trickling filter. Trickling filter

effluent is pumped back through the filter as recycle. Alternatively, the trickling filter can be

bypassed, in which case primary effluent flows by gravity directly to the aeration basin.

2·1

SAND

04/JLW"1

RAW BACKWASH ~ BLOWERS

0-=-TRICKUNG FILTER BYPASS AERATION SECONDARY

TRICKLING BASiN CLARIFIER FILTER

I I I

.... : 0 : II:: :0 :0. DID 0 00 • 0000000 DODoO Q

--00.0 0 0 III_ODD

I FILTERI I I AERATION BASIN BYPASS : __ 1 -' I I I I

~R

=:llI 0-__'-_~I __ =~~"-=--im ___ ISUPERNATANT

RETURNS ~_________________ I----------------

TABLE 2-1

SODUS VILLAGE WWTP - SUMMARY OF UNIT PROCESSES

Unit Process Number Description

Primary clarifier 1 Area =616 ft2

Volume =32,224 gal.

Diameter =28 ft

Trickling filter 1 Media depth =5 ft 3 in.

Diameter =35 ft

Aeration basin 1 Area =2,640 fe

Depth =15 ft

Volume =296,208 gal.

Diffusers Fine bubble

Rubber sock

Submergence depth =14 ft

Aeration blowers 5 lOhpeach

Secondary clarifier 1 Area =616 ft2

Volume =32,224 gal.

Diameter =28 ft

Tertiary sand filter 1 Area =352 ft2 total

2 blowers at 10 hp each

Digester 1 Volume =95,000 gal. Sludge concentrator 1 Screw conveyor

The trickling filter effluent is pumped to the aeration basin. Air is supplied through fine-pore rubber

sock diffusers by five 10-hp blowers. There is also a bypass of the aeration basin that sends trickling

filter effluent flow directly to the secondary clarifier. Bypassing is done to reduce the solids loading

on the secondary clarifier during high flow conditions. The solids concentration in the trickling filter

effluent is significantly less than the solids concentration in the aeration basin. The operator

estimates that approximately 50 percent of the total plant flow bypasses the aeration basin.

The wastewater flows by gravity from the aeration basin to the secondary clarifier. Sludge from the

secondary clarifier is removed from the bottom of the clarifier, the return activated sludge (RAS) is

returned to the head of the aeration basin, and the waste activated sludge (WAS) is pumped to the

sludge well. The RAS and WAS flow rates are not measured.

Secondary effluent is pumped to the effluent sand filter. Backwash operations of the filter are

controlled by level sensors and each cell is backwashed at least once a day. There are two 10-hp

backwash blowers. One blower operates continuously to provide reaeration of the filter effluent.

2-3

Sludge is pumped from the sludge well to the anaerobic digester. The sludge is recirculated through

a heat exchanger and is continuously mixed in the digester. The digested sludge is pumped from the

digester to a sludge concentrator for dewatering. The dewatered sludge is disposed of offsite.

Performance History

The average monthly flow to the Sodus Village WWTP between January 1986 and December 1995

was 0.34 mgd. Since 1986, the flow has been increasing at a rate of approximately 0.013 million

gallons per year. The average monthly BODs and the TSS loads to the plant between January 1986

and December 1995 were 495 and 470 lb/day, respectively. The average TSS and BODs

concentrations in the raw sewage were 168 and 174 mg/L, respectively.

When the aeration basin at the Sodus Village WWTP went online in January 1991, the final effluent

quality improved dramatically. Prior to 1991, the average concentrations were 31 mg/L for BODs,

23.4 mg/L for TSS, and 19.2 mg/L for ~-N. After 1991, the effluent concentrations improved to

7.9 mg/L for BODs,S mg/L for TSS, and 3.7 mg/L for ~-N.

During the summer months between 1991 and 1995, average monthly final effluent concentrations

were 5.0 mg/L, 4.3 mg/L, and 1.7 mg/L, for BODs, TSS, and ~-N, respectively. These compare

with the summer discharge criteria of 5 mg/L for BOD5' 10 mg/L for TSS, and 2.0 mg/L for ~-N.

During the winter months the average monthly final effluent concentrations were 9.0 mg/L, 5.9

mg/L, and 4.5 mg/L, for BOD5' TSS, and ~-N, respectively. These compare to the winter

discharge criteria of 25 mg/L for BODs and 30 mg/L for TSS. There is no discharge criterion for

~-N during the winter.

The average removal efficiencies of BODs, TSS, and ~-N for the Sodus WWTP between January

1986 and December 1995 were 78 percent for BODs, 85 percent for TSS, and 58 percent for NH3-N.

After 1991 the removal efficiencies improved to an average of approximately 96 percent for both

BODs and TSS, and 82 percent for ~-N.

The current discharge permit for the Sodus WWTP requires 85 percent removal efficiency for both

BODs and TSS. The removal efficiency for BODs was in excess of 85 percent 95 percent of the time

and for TSS was in excess of 85 percent 98 percent of the time.

The mixed liquor suspended solids (MLSS) concentration for the aeration basin at the Sodus WWTP

was 3,852 mg/L. High MLSS concentrations during the winter months of 1995 were the result of

2-4

solids-handling limitations during the winter. The sludge concentrator was not in a heated facility

and therefore the WWTP operator was not able to remove solids from the aeration basin. This

situation has been corrected and the MLSS concentrations have since decreased.

The average sludge volume index (SVI) for the Sodus WWTP from January 1995 to October 1996

was 139 mL/g. The SVI is used as an indicator of the settling characteristics of a sludge. Values

greater than 200 mL/g are associated with poorly settling sludge. The maximum SVI between

January 1995 and October 1996 was 176 mL/g.

The monthly average sludge volume feed to the digester was approximately 88,850 gallons, and the

monthly average discharge from the digester was 41,150 gallons. The difference between the

volume of sludge pumped to and the volume of sludge discharged from the digester (approxi

mately 47,700 gallons) is the amount of supernatant returned to the head of the plant from the

digester.

The average monthly electrical usage for the Sodus Village WWTP between July 1995 and October

1996 was 22,815 kWh/month, and the average monthly natural gas usage was 670 therm/month

(1 therm = 100,000 Btu). During the winter months the natural gas consumption increased to 1,113

therm/month. Natural gas is used to heat the digesters.

Field Test

The Sodus Village WWTP field test program was conducted from June 4 to June 28, 1996. Table 2-2

presents the unit process loadings and effluent quality during the field test program and historical

values for the facility. The hydraulic and organic loading during the field test program was similar

to the historical data for the facility. However, the final effluent characteristics were significantly

different. The field test final effluent characteristics were determined based on 24-hour composite

samples collected every second day. These concentrations are likely a more accurate reflection of the

loading and treatment provided by the Sodus Village WWTP.

Field testing consisted of offline sampling, online monitoring, and performance testing of specific

equipment and processes. The offline sampling results were based on 24-hour composite samples

and grab samples taken at various points in the process. The online data consists of data measured

from temporary instruments installed for the test period and from existing permanent metering

equipment onsite. The temporary instruments included DO probes installed in the aeration basin, a

solids probe in the aeration basin to measure mixed liquor suspended solids concentration, and a

2·5

TABLE 2-2

SODUS VILLAGE WWTP - SUMMARY OF UNIT PROCESS LOADING DURING FIELD TEST PROGRAM

Unit Process Units Field Test Historical Average Maximum Average Maximum

Loading Hydraulic Organic

BODs BODs TSS TSS ~-N

Mgd

mg/L lb/d

mg/L lb/d

mg/L

0.34

126 339 172 475 NA

0.46

280 710 500

1,691 NA

0.38

174 613 168 530 24

0.48

260 949 310 849 32

Effluent Quality BODs TSS NH,.-N

mg/L mg/L mg/L

19 11 6.7

40 28 19

7.9 5

3.7

Primary Clarifier Area ff 616 616 Surface overflow rate gpd/ff 551 750 620 780

Aeration Basin Volume BODs loading HRT

fe lb / day*l,OOO fe

hour

39,600 8.3 21

18 15

39,600 NA 18.7

NA 14.8

MLSS concentration SVI F/M

mg/L mL/g days·!

3,763 NA 0.06

4,800 NA 0.1

3,852 139 NA

8,904 176 NA

Secondary Clarifiers Area ff 616 616 Surface overflow rate gpd/ff 551 750 620 780

Tertiary Sand Filter Area ff 352 352 Hydraulic loading gpm/ff 0.66 0.9 0.75 0.95

Digesters Primary volume Feed Discharge HRT

gal. gal./month gal./month

days

95,000 44,300 30,500

65

95,000 88,840 41,140

33

solids probe in the secondary effluent well to measure secondary effluent suspended solids

concentration. The total plant flow was measured by the existing plant flow meter. The performance

testing consisted of oxygen transfer efficiency testing of the aeration equipment and pump

performance tests.

2·6

Table 2-3 presents a summary of the field test activities. Detailed test descriptions and results are

presented in the Sodus Village WWTP Site Report (CH2M IDLL, 1998e).

Sample Location

Raw sewage

Primary effluent

Trickling filter effluent

Secondary effluent

Sand filter effluent

Sludge concentrator supernatant

Filter backwash

Digester supernatant

Raw sludge

Digested sludge

Digester profile (5 ports)

MLSS

RAS

Location

Aeration basin

Secondary effluent

Raw sewage

Location

Aeration basin

Pumps

TABLE 2-3 SODUS VILLAGE WWTP - FIELD TEST PROGRAM

Offline Sampling Program

Frequency Type of Sample Analysis

2nd day 24h cBOD5, TSS, VSS

2nd day 24h cBOD5I ~-N, TKN, TSS, VSS

2nd day 24h cBOD5, NH3-N, TKN, TSS, VSS

2nd day 24h cBOD5I ~-N, TKN, TSS, VSS

2nd day 24h cBOD5I TSS, VSS

1I operation grab cBOD5I TSS, VSS

1I week grab cBOD5, TSS

grab cBOD5I TKN, TSS

grab TS, TVS

grab TS, TVS

grab TS, TVS

2/week grab TSS, VSS

2/week grab TSS

Online Monitoring Program

Type Data

Dissolved oxygen 4 temporary meters

Suspended solids 1 temporary meter

Suspended solids 1 temporary meter

Flow 1 existing meter - flume

Performance Testing

Type Analysis

Offgas Oxygen transfer efficiency

Performance "Wire to water" efficiency

2·7

The major conclusions from the field study period for the Sodus Village WWTP were:

• The average BODs and TSS removal efficiencies were 25 and 38 percent,

respectively. Typical BODs and TSS removal efficiencies for primary clarifiers are

35 and 65 percent, respectively. The poor performance was likely due to solids

buildup in the clarifier. The solids were removed once or twice per week.

• The trickling filter was providing only minimal treatment under current loading

conditions.

• The aeration basin operated as an extended aeration facility. The existing

aeration equipment was able to maintain the DO concentration over 1.0 mg/L at

all times. The average DO was greater than 3.0 mg/L for significant periods

during the study.

• The measured standard oxygen transfer efficiency (SOTE: 20oe, a mg/L ~O) of the existing aeration equipment was 21 percent.

• Pressure relief valves on the air piping were open between the aeration blowers

and the aeration basin, resulting in a constant venting of pressurized air to

atmosphere.

• The secondary clarifiers were not performing as expected. This was likely due to

a solids flux failure and bottlenecks in removing settled solids from the clarifier.

• The secondary effluent solids concentration regularly increased during the day.

The pattern observed indicated a solids flux limitation in the clarifier. The solids

removal mechanisms and RAS pumps should be upgraded if the secondary

clarifier remains in service.

• The NH3-N concentration in the final effluent averaged 6.7 mg/L, which is

greater than the effluent discharge requirement of 2.0 mg/L. This was likely the

result of directing flow from the trickling filter to the secondary clarifier, thus

bypassing the aeration basin. The operators bypassed the aeration basin to

reduce the solids loading to the secondary clarifier. The trickling filter did not

provide nitrification under current loading conditions.

2·8

• The check valves on the secondary pumps were not operating correctly, resulting

in pumped secondary effluent being returned to the wet well through the

standby pump.

• The biogas collection system for the anaerobic digester was inoperable. The

digester cover was corroded and leaked biogas to the atmosphere. The gas

collection system was plugged and the digester was venting through the

emergency overflow vent. This represented a significant health and safety

concern for the site, as well as a loss of useable energy.

VILLAGE OF GOSHEN WWTP

Figure 2-2 presents a flow schematic and Table 2-4 summarizes the unit processes of the Village of

Goshen WWTP. Wastewater, consisting mainly of domestic, institutional, and commercial sewage,

flows by gravity to the WWTP. The design capacity of the WWTP is 1.5 mgd and the current

measured average day flow is 1.23 mgd. The discharge criteria for the facility are 25 mg/L BODs

and 25 mg/L TSS.

The wastewater flows by gravity through a manually cleaned bar screen and grit chamber to a

distribution box that divides the flow among three primary clarifiers. The screenings and grit are

transported to a landfill. After primary clarification, the wastewater flows by gravity through two

trickling filters to the trickling filter wet well, where it is pumped to the secondary clarifiers.

Wastewater from the secondary clarifiers flows by gravity through the chlorine contact chamber to

the two effluent polishing lagoons. The effluent polishing lagoons are operated in series. The treated

effluent is discharged into the Rio Grande Creek.

Solids from the secondary clarifiers are pumped on a continuous basis to the primary clarifier

distribution box for co-settling in the primary clarifier. The combined sludge from the primary

clarifier is pumped twice per day to the primary anaerobic digester. A dual fuel gas boiler is used to

heat the digester contents. The digester is mixed for approximately 16 hours per day with a digester

recirculation pump. The primary digester mixing pumps are switched off for approximately eight

hours each day when the combined sludge is pumped into the primary digester.

Digested sludge flows by gravity from the primary to the secondary digester. Supernatant from the

secondary digester flows by gravity to the primary clarifier distribution box. Digested sludge is

2·9

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TABLE 2-4

VILLAGE OF GOSHEN WWTP - SUMMARY OF UNIT PROCESSES

Unit Process Number Description

Bar screen 1 Manual cleaned

Grit chamber 1 Circular

Primary clarifier 2 Area = 768 fe (per unit) 64 ft x 12 ft; 7.25 ft deep

1 Area = 960 fe (per unit) 60 ft x 16 ft; 7 ft deep

Trickling filter 2 Area = 2,827 fe (per unit) Volume = 19,792 fe Dia. = 60 ft; rock 7 ft deep

Secondary clarifier 2 Area = 936 fe 52 ft x 18 ft; 6.5 ft deep

Chlorine contact chamber 1 Area = 828 fe Volume = 4,140 fe

Polishing lagoons 1 Area = 10.5 acres Volume = 3.85 million gal.

1 Depth 12 to 15 inches Area = 10.5 acres Volume = 15.4 million gal. Depth 4.5 feet

Digester 1 Primary digester - fixed roof Max volume = (25,450 fe) 190,400 gal. Dia. = 45 ft; SWD = 16 ft

1 Secondary digester - floating roof Max volume = (35,000 fe) 261,800 gal. Dia. = 45 ft; SWD = 19 ft

Sludge drying beds 4 Area =11,250 fe (per unit)

removed from the secondary digester every 45 to 60 days. Approximately 25 to 30 cubic feet of

digested sludge are removed from the secondary digester and placed on sludge drying beds. The

drainage from the sludge drying beds is pumped to the primary clarifier distribution box.

Performance History

The average-day flow for the Village of Goshen WWTP for June 1995 to June 1996 was 1.23 mgd.

However, the flow is highly variable. During dry weather periods (June through September 1995) it

averaged between 0.7 and 1.0 mgd. During wet weather it increased to over 3.0 mgd. The flow

2-11

distribution pattern indicated there was a significant contribution from infiltration/inflow in the raw

sewage flow to the plant.

The historical TSS and BODs loadings to the Village of Goshen WWTP averaged 1,350 and 1,190

lb/day, respectively. The Sorrento cheese factory is the only major industrial source in the sewerage

area. During the first quarter of 1995, Sorrento's pretreatment system (activated sludge) experienced

process upsets, resulting in an increase in the organic load to the plant. As a result, the TSS and

BODs loadings were significantly greater during the first quarter of 1995. The average TSS and BODs

concentrations for January, February, and March 1995 were 241 and 173 mg/L, respectively. The

average TSS and BODs concentrations for the 19-month period of record examined were 135 and 124

mg/L, respectively.

The TSS and BODs concentrations in the final effluent from the Village of Goshen WWTP from

January 1995 to June 1996 were 3.8 and 2.8 mg/L, respectively. This is well below the effluent

discharge requirement of 25 mg/L for BODs and 25 mg/L for TSS. The average TSS and BODs

removal efficiencies were 96.6 percent and 97.2 percent, respectively. The WWTP provides a very

high standard of treatment. The BODs and TSS removal efficiencies were greater than 90 percent for

more than 98 percent of the time over the 18-month period examined.

The average daily volume of sludge pumped to the primary digester was 8,083 gallons per day. The

solids concentration in the co-settled sludge was not measured. The flow control gate on the sludge

withdrawal line from each clarifier is opened manually.

The average electrical consumption from November 1994 to July 1995 was 870 kWh per day. The

energy use remained significantly higher during the winter months. This was likely due to the

increase in flow rate and electrical heating requirements during the winter.

The average propane consumption from 1993 to 1996 was 9,925 gallons per year. Propane is used to

heat the primary digester. During the summer months of 1993 and 1994, biogas collected from the

primary digester was used for most of the heating requirements. During 1995 and 1996, the WWTP

was not able to collect biogas and therefore average propane consumption increased from 20.3 to

34.1 gallons per day.

2·12

Field Test

The Village of Goshen WWTP field test program was conducted from July 16 to August 15,1996.

Table 2-5 presents a comparison between the unit process loadings and effluent quality during the

field test program and historical values for the facility. The hydraulic loading to the treatment plant

was similar to the historical values. However, the raw sewage BODs and TSS concentrations were

significantly lower. The average BODs and TSS concentrations during the test period were 67.2 and

88.9 mg/L, respectively. Therefore, the organic loading on the Village of Goshen WWTP was

approximately half of the historical average for the facility.

TABLE 2-5 VILLAGE OF GOSHEN WWTP - SUMMARY OF UNIT PROCESS LOADING DURING FIELD TEST PROGRAM

Unit Process Units Field Test Historical

Average Maximum Average Maximum

Loading

Hydraulic Mgd 1.16 3.28 1.23 3.41

Organic

BODs Mg/L 67.2 96 124 Ibid 571 829 1,193 2,203

TSS mg/L 88.9 134 135 Ibid 807 1270 1,352 2,841

Effluent Quality

BODs Mg/L 1.9 3.0 2.8

TSS Mg/L 3.2 6.0 3.8

Primary Clarifier

Surface overflow rate Gpd/£e 464 1,314 492 1.362

Trickling Filter

Surface wetting rate Gpm/fe 0.14 0.40 0.15 0.42

BOD. loading rate a Ibid 1,000fe 7.8 16.6 19.6 36.2

Secondary Clarifiers

Surface overflow rate Gpd/fe 620 1,752 657 1,822

Chlorine Contact Chamber

Hydraulic residence time Min 38 14 36 13

Effluent Polishing Lagoons

Lagoon 1 HRT Day 3.3 1.2 3.1 1.1

Lagoon 2 HRT Day 13.3 4.7 12.5 4.5

Total Day 16.6 5.9 15.6 5.6

Primary Digester

Hydraulic residence time b Day 23.8 23.5

VS loading C VSSlb/day 400

Notes:

a Based on primary effluent average and maximum BODs of 311 and 658lb/day, respectively

b Based on measured sludge pump rate

C Based on mass balance around the primary clarifier

2·13

Field testing consisted of offline sampling, online monitoring, and performance testing of specific

equipment and processes. The offline sampling results were based on 24-hour composite samples

and grab samples collected at various points in the process. The online data consisted of data from

existing flow metering equipment supplemented with a temporary solids concentration meter in the

secondary clarifier effluent. The performance testing consisted of stress testing of the primary and

secondary clarifiers, a mixing evaluation of the primary digester, and performance testing of the

secondary effluent pumps. Table 2-6 summarizes the work done. Detailed test descriptions and

results are presented in the Village of Goshen WWTP Site Report (CH2M HILL, 1998c).

TABLE 2-6

VILLAGE OF GOSHEN WWTP - FIELD TEST PROGRAM

Offline Sampling Program

Sample Location Frequency Type of Sample Analysis

Raw sewage 2nd day 24h cBODs' TSS, VSS, ~-N, BODs, N02-N, N03-N, TKN

Primary effluent 2nd day 24h cBODs' NH3-N, TKN, TSS, VSS, BODs, Nq-N, N03-N

Trickling filter effluent 2nd day 24h TSS, VSS, cBODs' BODs, ~-N, N02-N, N03-N

Secondary effluent 2nd day 24h cBODS' ~-N, TKN, TP, TSS, VSS, BODS' N02-N, N03-N

Digester supernatant l/week grab cBODS' TKN, TP, TSS

Co-settled sludge 2/week grab TSS, VSS

Online Monitoring Program

Location Type Data

Secondary effluent Flow 1 existing meter - weir Suspended solids 1 temporary meter

Performance Testing

Location Type Analysis

Primary clarifier Stress test Capacity

Secondary clarifier Stress test Capacity

Pumps Performance "Wire to water" efficiency

Digester Profile Mixing

2·14

The main conclusions from the field study of the Village of Goshen WWTP were:

• Primary clarifier performance was poorer than expected. This was partly due to

poor hydraulic distribution among the three clarifiers.

• The secondary sludge pumps operated continuously, recycling an excessive

amount of water through the plant.

• The secondary pump on/off operation resulted in frequent pump cycling and

continual small hydraulic perturbations to the secondary clarifier. This had a

significant negative impact on clarifier performance.

• The hydraulic throughput of the plant was less than 3.5 mgd. Significant

hydraulic bottlenecks occurred at the plant headworks, between the primary

clarifier and trickling filter, and at the chlorine contact chamber outfall.

• The measured capacity of the primary clarifiers was 1.5 mgd. The capacity could

be increased by improving the flow distribution between the clarifiers.

• The measured capacity of the secondary clarifiers was 3.0 mgd. The secondary

clarifier performance was reduced due to the on/off operation of the secondary

pumps.

MARSH CREEK WWTP

Figure 2-3 presents a flow schematic and Table 2-7 summarizes the unit processes of the Marsh

Creek WWTP. Wastewater flows by gravity to the WWTP and consists mainly of domestic and

commercial sewage. Hauled leachate is brought to the plant and mixed with the raw sewage

upstream of the primary clarifier. The rated capacity is 4.0 mgd and the average day flow is 3.35

mgd. There are no bypass structures. All wastewater generated by the catchment area must be

treated by the plant. The discharge criteria for the facility are 30 mg/L BODs, 30 mg/L TSS, and 1.0

mg/L total phosphorus (TP).

The wastewater flows by gravity through the primary clarifiers, aeration basins, and the secondary

clarifiers, and receives chlorination before discharge. Primary sludge pumped from the primary

2-15

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TABLE 2-7

MARSH CREEK WWTP - SUMMARY OF UNIT PROCESSES

Unit Process

Primary clarifier

Aeration basin

Diffusers

Aeration equipment blowers

Secondary clarifier

Gravity thickener

Digester

Belt filter press

Compost facility

Number Description

2 Area = 707 fe (per unit)

Volume = 211,792 gal. (total)

Diameter = 30 ft

2 Area = 3,384 fe (per unit)

Volume = 750,000 gal. (total)

Depth = 14' 5"

Fine bubble Area per diffuser = 48 ft2 Number per tank = 38 Submergence = 13' 11"

2 60hp Variable speed, manually controlled

1 100hp Variable speed, manually controlled

2 Area = 707 ft2 (per unit)

Volume = 211,792 gal. (total)

Diameter = 30 ft

2 Volume = 77,141 gal. (per unit) Dia. = 25 ft2 Side wall depth = 16.5 ft

1 Primary

Volume = 500,000 gal.

1 Secondary

Volume = 500,000 gal.

1 Width =6ft

1 Capable of producing 2.5 dry tons of finished product per day

clarifiers passes through a grit classifier and then is pumped to a gravity thickener. Grit removed by

the classifier is disposed of offsite.

Air is supplied to the aeration basin by one 100-hp and two 60-hp blowers through fine bubble

membrane panel diffusors. WAS removed from the secondary clarifier is pumped to a gravity

thickener prior to being pumped to the primary digester.

There is one primary digester and one secondary digester. Sludge is fed to and removed from the

digesters by pumps. Hot water circulation is used to maintain the temperature in both digesters.

2·17

Methane gas produced by the digesters is used as the fuel source for heating, supplemented with

natural gas on an as-needed basis.

Sludge from the secondary digester is pumped to a belt filter press (BFP) for dewatering. Filtrate

from the BFP is fed back to the headworks of the plant. Dewatered sludge is moved by conveyor

from the BFP to the compost facility. The compost facility is a batch feed facility. Wood chips are

added to the sludge as an amendment material prior to composting. Three local businesses are

contracted to purchase the compost produced by the WWTP for use as a soil conditioner in

agricultural and horticultural activities.

Performance History

The average-day flow to the Marsh Creek WWTP between January 1995 and May 1996 was 3.35

mgd. There is a pronounced seasonal variation in flow, with low flows occurring during the dry

weather period of June to September. The minimum and maximum day flows for the period were

1.75 and 12 mgd, respectively. The hydraulic peaking factor was over 4.0. This high value indicates

an inflow and infiltration problem within the collection system.

The average BODs and TSS concentrations in the raw sewage flow to the WWTP for January 1995 to

May 1996 were 228 and 176 mg/L, respectively. The BODs concentration was reasonably consistent

over the period of record, but the TSS concentration fluctuated widely. The high BODs and the TSS

concentrations can be attributed to the introduction of leachate and hauled waste to the raw sewage

at the headworks of the plant as well as sewage from local food processing plants. The average ortho

phosphate (P04) concentration of the raw sewage between January 1995 and May 1996 was 2.7

mg/L. The average BODs and TSS loads to the plant were 6,032 lb/day and 4,908 lb/day,

respectively.

The average final effluent concentrations for BODs, TSS, and P04 were 22 mg/L, 10 mg/L, and 0.4

mg/L, respectively. The average concentrations for BODs and TSS are below the discharge criteria of

30 mg/L for both parameters. The average removal efficiencies were 90 percent, 90 percent, and 82

percent for BODy TSS, and P04' respectively.

The average MLSS concentration for the aeration basins at the Marsh Creek WWTP from January

1995 to May 1996 was 2,275 mg/L. The average solids residence time (SRT) for the WWTP was 3.9

days. The SRT was less than 6 days for over 95 percent of the time. The average food to

2·18

microorganism (F/Mv) ratio, based on the ratio of BODs loading to the aeration basin and the mixed

liquor volatile suspended solids (MLVSS) concentration, was 0.31 dail.

The RAS flow rate for the Marsh Creek WWTP is controlled by two single-speed pumps, each rated

for a capacity of 1 mgd. The flow is not measured but can be controlled by adjusting the pump

speed setting.

The average SVI was 84 mL/g. The low SVI indicated a very well-settling sludge.

The percentages of total dry solids that were volatile for both the raw and digested sludge were 69

percent and 55 percent, respectively. The volatile destruction in the primary digester was 45 percent.

The average hydraulic residence time (HRT) of the primary digester was 42 days.

The BFP is used to dewater the digested sludge prior to composting. The average percentage of

solids of the digested sludge feed to and from the BFP was 2.95 percent and 21 percent, respectively.

The average monthly electrical usage for the Marsh Creek WWTP was 124,235 kWh between

January 1995 and May 1996. There appeared to be a trend of increasing electrical usage by the

WWTP over the 15-month period. This was likely due to increased influent flow and increased

organic load to the aeration basin.

Field Test

The Marsh Creek WWTP field test program was conducted from May 28 to June 28,1996. Table 2-8

presents a comparison between the unit process loadings and effluent quality during the field test

program and historical values for the facility. The unit process loadings were similar to historical

values.

Field testing consisted of offline sampling, online monitoring, and performance testing of specific

equipment and processes. The offline sampling results were based on 24-hr composite samples and

grab samples taken at various points in the process. The online data consists of data from permanent

plant monitoring equipment supplemented with temporary instruments. The following parameters

were measured using permanent instrumentation: plant flow, RAS flow, WAS flow, and air flow.

The temporary instruments included DO probes and an MLSS probe in the aeration basins.

Performance testing included oxygen transfer efficiency testing of the aeration equipment and a

2·19

TABLE 2-8

MARSH CREEK WWTP - SUMMARY OF UNIT PROCESS LOADING DURING FIELD TEST PROGRAM

Unit Process Units Field Test Historical

Average Maximum Average Maximum

Loading Hydraulic Organic

BODs

TSS

Mgd

Ibid mg/L Ibid

mg/L

3.63

6,015 199

7,255 240

12.64

NA 282 NA 425

3.35

6,032

4,908

12

9,762'

13,026'

Primary Clarifier (1,414 ff) Surface overflow rate Gpd/fe 2,567 8,939 2,369 8,486

Aeration Basin (200,520 fe) BODs loading rate MLSS concentration

lbI d per 1,000 fe mg/L

17.0 1,942

33.5 2,340

18.7 2,275

Secondary Clarifiers (1,414 fe) Surface overflow rate Solids loading rate

Gpd/fe lb/hper fe

2,567 2.7

8,939 3.9

2,369 1.9

8,486 6.7

Belt Filter Press Solids concentration in Solids concentration out

% %

2.7 23.2

2.9 21

Note: Maximum values are 95th percentile values from historical review.

tracer test on the primary digester. Table 2-9 presents a summary of the field test activities. Detailed

test descriptions and results are presented in the Marsh Creek WWTP Site Report (CH2M HILL,

1998d).

The major conclusions from the field study of the Marsh Creek WWTP were:

• The organic loading to the Marsh Creek WWTP was highly variable. This was

likely the result of the hauled leachate and industrial wastewater received at the

site.

• The increase in organic loading that started Monday mornings had a negative

impact on the DO concentration in the aeration basins. The DO was less than 1.0

mg/L for most of the day and recovered at night and on the weekends. BOD

2·20

TABLE 2-9

MARSH CREEK WWTP - FIELD TEST PROGRAM

Offline Sampling

Sample Location Frequency Type of Sample Analysis

Raw sewage Daily 24h CBODs, TSS, VSS, TP

Primary effluent Daily 24h CBODs, NJ\-N, TSS, VSS, TP

Secondary effluent Daily 24h CBODS' TKN, TSS, TP, N03-N, N02-N, NH3-N

Gravity thickener l/week grab TS/TSS, VSS info & eff.

Gravity thickener l/week grab CBODS' TS/TSS, TP, TKN recycle

Belt press in & out l/week grab TS

BFP filtrate l/week grab TKN, TP, cBODs, TSS, NJ\-N

MLSS 2/week grab TSS, VSS

RAS 2/week grab TSS

Leachate NA grab CBODS' NJ\-N, TSS, VSS

Online Monitoring Program

Location Type Data

Raw sewage Flow 1 existing meter - magmeter

RAS Flow 2 existing meters - magmeter

WAS Flow 1 existing meter - magmeter

Air Flow 1 existing meter - orifice plate

Aeration basin Dissolved oxygen 5 temporary meters Solids (MLSS) 1 temporary meter

Performance Testing

Location Type Analysis

Aeration basin Offgas Oxygen transfer efficiency

Digester Tracer Mixing

breakthrough occurred occasionally. Final effluent concentrations were greater

than 60 mg/L.

• The measured standard oxygen transfer efficiency (SOTE: 20°C, 0 mg/L DO) of

the membrane panel aeration system was 18 percent.

2-21

• Marsh Creek WWTP provided partial nitrification during the first two weeks of

the study period, and almost complete nitrification during the second two weeks.

The switch from partial to full nitrification did not have a negative impact on the

effluent quality.

• Hydraulic loading increased rapidly during storm events, from an average of

3.35 mgd to 12 mgd. However, the sudden increase in flow did not have a

negative impact on the TSS concentration in the final effluent.

• The digester provided 45 percent volatile solids destruction. The level of volatile

destruction was lower than expected. Expected reduction in volatile solids was

between 50 and 55 percent. This may have been the result of poor mixing in the

digester.

• The measured active volume of the primary digester was 79 percent of the total

volume available. Approximately 6 percent of the pumped sludge short-circuited

the digester volume.

ARLINGTON SEWAGE TREATMENT PLANT

Figure 2-4 presents a flow schematic and Table 2-10 summarizes the unit processes of the Arlington

sewage treatment plant (STP). Wastewater, consisting mainly of domestic, institutional, and com

mercial sewage, flows by gravity to the STP. The design capacity of the STP is 4.0 mgd and the

current average-day flow is 3.44 mgd. The discharge criteria for the facility are 30 mg/L BODs and

30 mg/L TSS. The plant does not have an ammonia removal requirement. However, operators are

required to measure the ammonia concentration and include the result as part of the monthly

summary report to the NYSDEC.

The wastewater flows by gravity through a coarse bar screen to the aerated grit chamber and

comminutor. The screenings and grit are transported to a landfill. The degritted sewage flows by

gravity to a primary clarifier distribution chamber. Supernatant from sludge thickeners and filtrate

from the BFP are combined with the raw sewage and the combined flow is distributed to four

primary clarifiers. The primary sludge is pumped from the primary clarifiers to the gravity

thickeners.

2·22

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TABLE 2-10

ARLINGTON STP - SUMMARY OF UNIT PROCESSES

Unit Process

Bar screen

Grit chamber

Primary clarifier

Aeration basin

Diffusers

Aeration equipment blowers

Secondary clarifier

Chlorine contact chamber

Gravity thickener

Belt filter press

Incinerator

Number

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3

(2 in service)

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Description

Mechanical clean

Aerated with dedicated blower

Area =2,088 fe (per unit) 116 ft x 18 ft; 8.67 ft deep Area =891 ft2 (per unit) 49.5 ft x 18 ft; 8.33 ft deep

Area =3,942 fe (per unit) Volume =45,176 ft3 (per unit) Depth =12ft Coarse bubble Area per diffuser =14 fe Number per tank =280 Submergence =11.5 ft 60hp Positive displacement, variable speed drive 60hp Positive displacement, split ring drive

Area =2,088 fe (per unit) 116 ft x 18 ft; 8.67 ft deep

Area =695 fe (per unit) Volume =4,517 fe (per unit) Volume =5,772 fe (per unit) Dia. =26 ft; depth =10 ft Width =1m Fluidized bed 800 lb Ihr dry solids

The primary clarifier effluent is recombined in a common primary effluent channel that connects the

three aeration basins. Under loading conditions prior to and during the test, two of the three

aeration basins were in service. The aeration basins can be operated as plug-flow or step-feed basins.

Air is provided to the aeration basins by three positive displacement blowers. Two of the three

blowers have variable-frequency drive systems, and the third blower has a manually operated split

disk drive system. The Arlington STP has an automatic DO control system, which operates the

blowers based on the DO measurement in the aeration basin.

2-24

The Arlington STP has three rectangular secondary clarifiers. There is an approximately lO-foot

hydraulic drop between the aeration basins and the secondary clarifiers. In the past, air entrainment

due to the free-fall discharge and turbulence in the aeration basin discharge channel was a problem.

The operators use an automated valve to control the water surface level in the aeration basin

discharge channel to ensure that the aeration basin outfall remains flooded and the pipe to the

secondary clarifier is submerged at all times.

The RAS is pumped from the secondary clarifier to the head of the aeration basin. Two RAS pumps

service three clarifiers. The RAS is measured with magnetic flow meters located at the entrance to

each aeration basin. Sludge is wasted from the RAS line using a manually operated bypass valve

located on the combined RAS line. The WAS is combined with the primary sludge in the gravity

thickeners.

The secondary effluent flows by gravity through the chlorine contact chamber and to final discharge

in the Hudson River.

The Arlington STP has two bypass systems, the stormwater bypass and the secondary bypass. The

stormwater bypass uses an overflow weir to divert raw sewage from the primary clarifier

distribution chamber to the inlet channel for the secondary clarifiers. The secondary bypass uses an

overflow weir to divert primary effluent from the aeration basin inlet channel to the chlorine contact

chamber. During a storm event, flows in excess of 4.5 mgd receive primary clarification and

disinfection only, and flows in excess of 6.0 mgd receive secondary clarification and chlorination

only. The maximum flow to the Arlington STP is 8.0 mgd. Therefore, the maximum flow to the

primary clarifiers is 6.0 mgd, the maximum flow to the aeration basins is 4.5 mgd, and the

maximum flow to the secondary clarifiers is 6.5 mgd (4.5 mgd from the aeration basin and 2.0 mgd

from the stormwater bypass).

Solids from the primary clarifiers are pumped to the gravity thickener for co-thickening with the

WAS. The thickened sludge is then pumped to the BFP and into the sludge incinerator. Since

February 1996, the BFP and sludge incinerator have operated for approximately six hours every day

(during the evening shift). Prior to this date, the belt press and incinerator operated approximately

once per week.

2·25

Performance History

Ihe average-day flow to the Arlington SIP was 3.45 mgd between January 1995 and June 1996, and

the maximum instantaneous flow recorded was 8.9 mgd. Therefore, the hydraulic peak factor is

approximately 2.5 for the period of record.

The ISS and BODs concentrations in the raw sewage flow to the Arlington SIP for January 1995 to

June 1996 were 124 and 130 mg/L, respectively. The average ISS and BODs loadings to the

treatment plant were 3,542 and 3,6741b/day, respectively.

The average ISS and BODs concentrations in the final effluent from the Arlington SIP from January

1995 to June 1996 were 7.5 and 6.7 mg/L, respectively. This is well below the effluent discharge

requirement of 30 mg/L for each parameter. The average BODs and ISS removal efficiency for the

facility was 94 percent. The Arlington SIP provides a good standard of treatment. The BODs and

ISS removal efficiencies were greater than 90 percent approximately 80 percent of the time between

January 1995 and June 1996.

The average MLSS concentration in the two aeration basins in service was 1,050 mg/L. The MLSS

concentration was significantly lower in the warmer period (wastewater temperature) of June

through October. During this time, operators have reduced the solids inventory in the aeration basin

by reducing the MLSS concentration in an attempt to prevent nitrification. The average MLSS

concentration for the months of November through June was 1,150 mg/L; the average MLSS

concentration for the months of July through October was 720 mg/L.

The F/Mv ratio for the Arlington SIP during the 18-month period was 0.65 dail. The F/Mv ratio

was very high in September and October 1995 due to the low MLSS concentration in the aeration

basin at the time. The SRI for the plant from January 1995 to June 1996 was 4.9 days. Other than on

a few days, the SRI remained below six days for the period of record.

The average solids concentrations for the thickened and dewatered sludge from January 1995 to

December 1995 were 3.6 and 20.6 percent dry solids, respectively. Starting in February 1996, the

Arlington SIP operated the dewatering and incineration process every day during the evening shift.

Prior to February, the dewatering and incineration process was operated once a week for

approximately 36 hours. Ihe change in operation resulted in an increase in the dewatered sludge

solids concentration from 20.6 percent dry solids in 1995 to 25.6 percent dry solids in July 1996. The

2-26

solids concentration in the dewatered sludge had a significant impact on the fuel consumption in the

incineration process.

The average electrical consumption for the Arlington STP from December 1993 to June 1996 was

5,270 kWh/day. The average oil consumption from January 1995 to June 1996 was 180 gallons per

day. The fuel oil was primarily used for the sludge incineration process. The average oil

consumption per pound of solids processed was 65 gallons/lb during 1995 and 12 gallons/lb in July

and August 1996. As noted above, the incinerator oil consumption was influenced by the solids

concentration in the dewatered sludge.

Field Test

The Arlington STP field test program was conducted from July 17 to August 25, 1996. Table 2-11

presents a comparison between the unit process loadings and effluent quality during the field test

program and historical values for the facility. The hydraulic and organic loadings to the treatment

plant were similar to the historical values.

Field testing consisted of offline sampling, online monitoring, and performance testing of specific

equipment and processes. The offline sample results were based on 24-hour composite samples and

grab samples taken at various points in the process. The online data consists of data measured from

temporary instruments installed for the test period and the existing online metering equipment at

the site. The temporary instruments included 00 meters installed in the aeration basin, solids

concentration meters in the aeration basin, and solids concentration meters in the final effluent. Plant

metering was used to monitor raw sewage flow, RAS flow, WAS flow, and total air flow. The

performance testing consisted of oxygen transfer efficiency testing of the existing aeration

equipment, and "wire to water" performance testing of the aeration blowers, incinerator fan, and

the RAS pumps. Table 2-12 summarizes the work done. Detailed descriptions and results are

presented in the Arlington STP Site Report (CH2M HILL, 1998a).

The main conclusions from the field study period for the Arlington STP were:

• The primary clarifiers performed well. The average BODs and TSS removal

efficiencies were 47 percent and 65 perce